High pressure wire reinforced hydraulic hose is typically used in a variety of applications, for example, to provide a flexible connection between several moving parts of hydraulic circuits where one part must move relative to the other part. Typical reinforced hydraulic hose structures are illustrated in U.S. Pat. No. 3,357,456 which issued on Dec. 12, 1967, to C. E. Grawey; and U.S. Pat. No. 4,262,704 which issued on Apr. 21, 1981, to C. E. Grawey.
One of the critical areas of such hydraulic hose is the liner or core structure. In both of the aforementioned patents, the liner member is formed by wrapping a laminated tape in overlapping relationship on a mandrel and then winding a series of wire plies with layers of elastomer between adjacent wire plies. The laminate tape is composed of two layers of uncured elastomer with an open mesh fabric sandwiched there between. A problem associated with such a method of manufacture is that the length of the hose produced is limited by the length of the calendered laminate tape stock roll. Also undesirably, the manufacture of the laminate tape is a time consuming, labor intensive, relatively expensive multistep process that has a considerable waste by-product that cannot be recycled.
Several processes have been developed to manufacture high pressure hose on a continuous basis. An example of such a process is set forth in U.S. Pat. No. 4,501,629 which issued on Feb. 26, 1985, to R. L. Satzler. The liner is formed by extruding a viscous material onto a mandrel.
U.S. Pat. No. 3,933,960 which issued on Jan. 20, 1976, to James Cameron et al. illustrates a method of making a reinforced tube having short discontinuous fibers incorporated in the viscous material. The fibers are circumferentially orientated to provide the necessary strength to resist internal pressures. When viscous material containing discontinuous fibers is extruded, the flow will cause the fiber to orientate axially in the direction of the flow. Examples of the discontinuous reinforcing fibers are shown in U.S. Pat. No. 3,697,364 which issued to K. Boustany et al. on Oct. 10, 1972, and U.S. Pat. No. 3,709,845 which issued to K. Boustany et al. on Jan. 9, 1973.
The subject invention provides a relatively simple extruding apparatus for the manufacture of a hose liner, on a continuous basis, in which discontinuous fibers are spirally orientated within the viscous polymer material as it is being extruded around the mandrel. The extruding apparatus controls the spiral orientation of the fibers, increases the liner's radial strength, provides smooth outer peripheral surfaces, provides a liner with a constant wall thickness, and bridges the space between the wires. With such construction, there is realized a savings of equipment, labor, and natural resources.
The present invention is directed to overcome one or more of the problems as set forth above.